1. Field of the Invention
The present invention generally relates to isolating a pressurized hot water heater tank from a pressurized water source system and, more particularly, is concerned with completely closing a control valve disposed between the water source and the hot water tank. A diaphragm attached to the control valve senses the pressure differential between the water source and the pressure in the connecting line which allows communication between the control valve and a check valve. The check valve controls the water flow from the hot water tank to the hot water domestic system or the household user.
2. Description of the Prior Art
Almost all buildings have hot water heaters in various forms. Conventionally, the heaters are connected from a pressurized supply line which contains cold water to the domestic hot water system. Usually, hot water heaters include a storage tank that is heated by a source of energy, for example, natural gas or electricity, which is controlled by a thermostat or the like.
Hot water heaters usually require little or no maintenance. However, due to the mineral contents of the water the interior of the tank often corrodes which weakens the structure of the heater tank. A leak or rupture usually occurs due to the weakened tank structure. The amount of water loss may vary due to various reasons such as the size of the leak. Furthermore, in the event that the temperature within the heater tank becomes excessive, the pressure within the heater becomes excessive, which could lead to a rupture.
To minimize the amount of water loss, various systems have been proposed in the past for isolating the source system when a leak or rupture occurs. For example, in U.S Pat. No. 3,063,432 to Bond, a can is disposed beneath the water heater. When a leak occurs the water would be collected in the can which would activate a switch. This opens a circuit causing the fuel supply and water supply to be cut off.
A similar apparatus is disclosed in U.S. Pat. No. 2,724,401 to Page. Various other structures have been proposed but have not been very economical.
A significant improvement for isolating the hot water heater tank from the source system was disclosed in U.S. Pat. No. 3,754,563 to Boals. The patent describes a valve controlling the flow between the source system and the hot water tank. The valve would be controlled by a diaphragm sensing the pressure differential between the domestic system and the heater tank. The apparatus disclosed by Boals works quite well in most applications but incorporates numerous seals which, under some operating conditions, could deteriorate. Furthermore, the Boals U.S. Pat. No. 3,754,563 apparatus does not provide for the passage of cold water into the hot water heater when an excessive temperature is reached.